1. Field of the Invention
The present invention relates to an improved semiconductor package and a method for manufacturing such a package.
2. Description of the Related Art
Generally, a semiconductor chip is mounted on a substrate such as a tape wiring substrate, a ceramic wiring substrate or a printed circuit board. The semiconductor chip is then electrically connected to the substrate by wire bonding. The wire bonding process typically uses a capillary or a wedge device to connect bonding wires between chip pads on the semiconductor chip and corresponding substrate pads on the substrate.
The conventional wire bonding process, however, may damage the chip pads due to the force which may be applied to the chip pads by the capillary or wedge device as it attaches the bonding wires. Wire bonding methods may also cause defects when bonding wires warp, roll or shift as result of the flow of liquid epoxy molding compound (EMC) during the encapsulation process, shocks during transportation and other mechanical forces absorbed by the bonding wires. Warped, rolled and shifted bonding wires will tend to decrease the yield and/or reliability of the resulting devices.
Conventional wire bonding methods require a predetermined height above the active surface of the semiconductor chip for the formation and maintenance of the bonding wire loops. Although there are variations of this height requirement depending on the diameter of the bonding wires and the particular bonding method utilized, conventional wire bonding will typically require heights between 100 μm and 200 μm. Therefore, conventional wire bonding methods are limited in their ability to realize thin packages.
Crossing bonding wires in conventional cross bonding methods increase the risk of short circuit between the upper and lower bonding wires. To reduce the likelihood of short circuits, the height of the loops of the upper bonding wires are typically increased above that used for the lower bonding wires to increase the separation between the wires, consequently increasing the thickness of the resulting semiconductor packages.